text: /*	$OpenBSD: fixunssfdi.c,v 1.5 2005/08/08 08:05:35 espie Exp $ */
  /*-
   * Copyright (c) 1992, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This software was developed by the Computer Systems Engineering group
   * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
   * contributed to Berkeley.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include "quad.h"
  
  #define	ONE_FOURTH	((int)1 << (INT_BITS - 2))
  #define	ONE_HALF	(ONE_FOURTH * 2.0)
  #define	ONE		(ONE_FOURTH * 4.0)
  
  /*
   * Convert float to (unsigned) quad.  We do most of our work in double,
   * out of sheer paranoia.
   *
   * Not sure what to do with negative numbers---for now, anything out
   * of range becomes UQUAD_MAX.
   *
   * N.B.: must use new ANSI syntax (sorry).
   */
  u_quad_t
  __fixunssfdi(float f)
  {
  	double x, toppart;
  	union uu t;
  
  	if (f < 0)
  		return (UQUAD_MAX);	/* ??? should be 0?  ERANGE??? */
  #ifdef notdef				/* this falls afoul of a GCC bug */
  	if (f >= UQUAD_MAX)
  		return (UQUAD_MAX);
  #else					/* so we wire in 2^64-1 instead */
  	if (f >= 18446744073709551615.0)	/* XXX */
  		return (UQUAD_MAX);
  #endif
  	x = f;
  	/*
  	 * Get the upper part of the result.  Note that the divide
  	 * may round up; we want to avoid this if possible, so we
  	 * subtract `1/2' first.
  	 */
  	toppart = (x - ONE_HALF) / ONE;
  	/*
  	 * Now build a u_quad_t out of the top part.  The difference
  	 * between x and this is the bottom part (this may introduce
  	 * a few fuzzy bits, but what the heck).  With any luck this
  	 * difference will be nonnegative: x should wind up in the
  	 * range [0..UINT_MAX].  For paranoia, we assume [INT_MIN..
  	 * 2*UINT_MAX] instead.
  	 */
  	t.ul[H] = (unsigned int)toppart;
  	t.ul[L] = 0;
  	x -= (double)t.uq;
  	if (x < 0) {
  		t.ul[H]--;
  		x += UINT_MAX;
  	}
  	if (x > UINT_MAX) {
  		t.ul[H]++;
  		x -= UINT_MAX;
  	}
  	t.ul[L] = (u_int)x;
  	return (t.uq);
  }
  